This invention relates to dental prostheses and more particularly to an oral implant that is installed in the jawbone for holding a dental prosthesis.
Oral implants serve as the foundation for a dental prosthesis and thus must have sufficient strength and stability to withstand the usual mandibular pressures. The structure of the implant and the manner in which it is installed in position in the jawbone are determinants in the ability of the implant to maintain its installed position over long periods of time.
Existing systems for installing an implant generally include a press-fitting of the implant in a drilled hole in the jawbone, a threading of the implant in a tapped hole in the jawbone, or a threading of the implant in a trephine drilled hole to accommodate a basket-type implant.
For example, U.S. Pat. No. 4,531,916 shows a dental implant that is press-fitted in a hole. Since the press-fit lacks a rigid attachment, making it vulnerable to movement, there is a need to provide apertures in the implant that permit ingrowth of bony tissue to assure a rigid attachment. Nevertheless, the implant as installed is vulnerable to movement and the potentials of nonhealing.
U.S. Pat. No. 4,259,072 shows a threaded implant that requires a tapping operation in the jawbone following the initial drilling of a precision hole. Although threading of the implant in the bone may provide more stability than a press-fit attachment, the implant is still vulnerable to movement. Thus it is usually necessary to rely on growth of new bone tissue and new connective tissue to further stabilize the installed position of the implant.
U.S. Pat. No. 4,431,416, shows a basket-type implant comprising an inverted cylindrical cage or basket that fits around a cylindrical bone core and into an annular recess formed by a trephine drill. The basket-type implant requires drilling of multiple holes and the breaking away of bone plug portions before drilling is resumed. Tapping of the hole to accommodate a threaded surface of the basket-type implant is also occasionally desired. The basket-type implant thus requires an extremely complex installation procedure that might discourage widespread use of such implant.
It is thus desirable to provide an oral implant that can be simply installed in a drilled hole, and does not rely on press-fitting, threading or trephine drilling to provide a stable, rigid positioning of the implant in the jawbone.